Abstract: Recently a 10 Hz operation modality of ILC linac has been proposed to optimize the collider performances at energies lower than the nominal one. One of the main concern on the feasibility of the 10 Hz modality is represented by the operation of the superconducting cavities in rapidly changing beam loading conditions. The most straightforward solution is to operate the cavities tuned at a fixed optimal frequency, at the price of a certain amount of mismatch and inefficiency in the RF system. In this memo expressions for calculating the optimal values of cavity detuning and cavity input coupling are derived. In the last part of the report the damping ring RF system parameters are evaluated, using the relations derived in the previous paragraphs, to optimize all the proposed operating configurations.